Sunscreen compositions are typically categorized as either aqueous or non-aqueous, i.e, anhydrous, compositions. Aqueous sunscreen compositions are typically creams formed as emulsions containing the active UV absorbing compounds and additional ingredients such as waterproofing agents, fragrances, emollients and other skin care ingredients. Non-aqueous sunscreen compositions are those that are typically solvent based compositions that can be formed as gels for topical application or sprayed on, for example from an alcohol based solution of the ingredients.
Sprayable sunscreen compositions have become popular in recent years as a means for transporting and applying sunscreen. Film forming polymers are known to be added to non-aqueous sunscreen compositions to provide water resistance to these compositions after application to a surface such as skin or hair. However, it has been determined that the addition of the film forming polymers beyond a certain amount can have a deleterious effect on the feel of the composition on the skin, in particular providing a caking feeling. Neutralizing agents have been used in connection with film forming agents contained in aqueous sunscreen emulsion formulations. See, e.g., WO 2004/071749 (Connetics Australia Pty. Ltd.) discussing limiting the amount of neutralizing agent added to aqueous formulations to preserve film forming properties.
In an effort to improve the skin feel of topically applied anhydrous sunscreen compositions that employ film forming polymers as waterproofing agents, the inventors have discovered that certain neutralizing agents provide not only the desired improved skin feel, but also provide an unexpected substantial boost in SPF values. Thus, compositions and methods employing such neutralizing agents to provide for improved sunscreen protection would be useful. These and other objectives are provided by the invention described herein.
All patent and non-patent references cited herein are hereby incorporated in their entirety into this specification by reference thereto. Identification or discussion of any reference in this section or any part of this specification shall not be construed as an admission that such reference is available as prior art to the present application.